On the asymmetry of biological frequency distributions.
The long-standing problem of determining whether the skewness in a sample frequency distribution is the manifestation of the intermixing of disparate groups characterizable by a normal mixture distribution or the manifestation of non-mixture, skew-producing determinants is discussed. Biometrical tools for modeling and quantifying the significance of the skewness in a trait of interest that invite interpretations other than those formed in mixtures or "subgroups" are elaborated. Statistical methods for testing whether a normal mixture distribution better characterizes a set of data than the proposed (or any other) skewed, single-population-oriented models are offered. The power of these tests is examined through Monte Carlo experimentation. A brief application in hypertension research demonstrates some of the problems and methods discussed in the paper.
Schork
N J
NJ
Department of Medicine, University of Michigan, Ann Arbor 48109-0500.
Weder
A B
AB
Schork
M A
MA
D001794:Blood Pressure / Q000235:genetics; D005821:Genetic Techniques; D006801:Humans; D015233:Models, Statistical; D009010:Monte Carlo Method; D016011:Normal Distribution; D013223:Statistics as Topic